The disclosure describes a system for pressurizing a fluid. The system includes a source of liquid fuel, a pressure build chamber in fluid communication with the source of liquid fuel such that the pressure build chamber is configured to receive a volume of liquid fuel from the source, wherein the pressure build chamber is configured to heat a portion of the volume of liquid fuel to a sufficient temperature to convert the portion of the volume of liquid fuel into a gaseous fuel or supercritical fluid, and wherein the pressure build chamber is configured to increase a pressure of a fluid in the pressure build chamber to a threshold pressure to inject the gaseous fuel or supercritical fluid into an engine.